In U.S. Pat. No. 5,413,077 of common assignee herewith, there is disclosed a returnless fuel pressure regulator which can be mounted on or adjacent the fuel rail assembly close to the fuel injectors and which regulator avoids any need for a return line to the fuel tank. The regulator disclosed in that patent also includes an intake manifold vacuum reference which essentially alters the calibration pressure of the regulator dependent upon throttle position.
A further modification of the pressure regulator illustrated in that patent is described and illustrated in U.S. patent application Ser. No. 09/056,044, filed Apr. 6, 1998 (Attorney Docket No. 98P7662). In that application, the check valve spring is formed of a shape memory alloy. The spring is responsive to a predetermined temperature to alter the fuel flow and/or pressure characteristics of the regulator and functions as a switch for providing regulated pressure or non-regulated pressure.